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C

Gervais Lake

Ramsey County, MinnesotaEutrophic

Gervais Lake earns a C — middle-of-the-pack water quality, with one or two parameters dragging the average down from a stronger grade. clarity and phosphorus rate similarly, so there is no obvious single lever to pull on watershed management.

A TSI in the eutrophic range signals a lake doing what nutrient-loaded waters do — supporting an active algal community at the cost of clear water. Gervais Lake reaches 41 ft at its deepest point — typical for Minnesota mid-sized lakes, with seasonal stratification but limited cold-water refuge. The lake's 235 acres and 3.3 miles of shoreline put it in the mid-range bucket — large enough for varied use, small enough that watershed inputs reach the whole basin. Within Ramsey County's 49 graded lakes, Gervais Lake ranks 29 — below the local median, though not at the bottom.

Gervais Lake is on the Minnesota infested-waters list for zebra mussels — boaters should follow clean-drain-dry protocols when moving gear to or from the lake. Muskie are on the species list at Gervais Lake, among the lake's 14 documented fish. The lake lacks a documented public access point, so visitor use is limited. Ice-out has been logged at Gervais Lake more than two dozen times, putting the median around Apr 3 — a useful baseline for tracking climate trends. Monitoring depth is thin here: the LakeGrade rubric is applied to a small number of sample years, and the grade will be revised as more data accumulates.

Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-09-17. Grade methodology: LakeGrade methodology.

Reviewed by LakeQuality Editorial Team · Updated

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Swimming Safety

Generally safe for swimming, moderate water quality

Water Quality Grade: C, Fair

Murky, only visible to about 6.2 ft. Phosphorus level: 38 µg/L. Trophic State Index: 54.

MetricValueGrade
Water Clarity (Secchi Depth)6.2 ftD
Phosphorus38 µg/LC
Chlorophyll-a (Algae)No data
Trophic State Index (TSI)54Eutrophic

High nutrients, frequent algae, reduced clarity

Lake Details

CharacteristicValue
Maximum Depth41 ft
Surface Area235.01 acres
Shoreline Length3.3 mi
Littoral Zone39%
Public AccessNo

Fish Species

black bullhead,black crappie,bluegill,common carp,green sunfish,hybrid sunfish,largemouth bass,northern pike,pumpkinseed,tiger muskellunge,walleye,white sucker,yellow bullhead,yellow perch

Click a species to see all Minnesota and Wisconsin lakes where it is found.

→ Best fishing times for Gervais Lake (14-day solunar calendar)

→ Is it safe to eat fish from Gervais Lake? (mercury & PFAS guide)

Gervais Lake fishing regulations (limits, seasons, special rules)

Invasive & Introduced Species

Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.

Eurasian watermilfoilzebra mussel

Water Quality Trend: Declining

Based on 5 years of monitoring data (2020-2025).

MetricTrendChange/YearYears
Water Clarity Declining-0.14 m/yr5
Phosphorus Stable-0.55 µg/L/yr5
See year-by-year chart →

Ice Season

Historical ice data from Minnesota DNR (60 observations).

Typical Ice-Out
Apr 3
Typical Ice-In
Dec 4

Estimated open water season: 245 days

EarliestLatest
Ice-Out2024-03-07 (2024)2018-04-30 (2018)
Ice-In2014-11-15 (2014)2001-12-20 (2001)

Most recent ice-out: 2026-03-29

Location

Loading map…

County Ranking

Ranked #29 of 49 lakes in Ramsey County

Cleaner Lakes Within 30 Miles

Gervais Lake holds Grade C. 4 nearby lakes hold higher grades.

See full comparison →

Nearby Lakes in Ramsey County

DNR Fisheries Survey Summary

12 surveys on file from MN DNR Fisheries. Most recent: 2021-09-07 (Targeted Survey).

Top Species by Catch Rate

SpeciesAvg CPUEAvg Weight
Bluegill62.000.14 lb
Green Sunfish9.610.06 lb
Black Crappie9.590.18 lb
Spottail Shiner8.71
Yellow Perch7.410.13 lb
Largemouth Bass7.270.9 lb

CPUE = catch per unit effort, averaged across surveys (excludes juvenile shoreline seining). Higher CPUE = more abundant in standardized sampling.

Length Distributions

Number of fish caught at each inch class in the most recent survey that recorded lengths. Red dashed line marks an approximate trophy threshold for that species.

Bluegill

192 fish · 27 in · 2021-09-07
67340234567

Green Sunfish

1 fish · 44 in · 2020-07-13
104

Black Crappie

11 fish · 59 in · 2021-09-07
320trophy 1056789

Yellow Perch

2 fish · 67 in · 2021-09-07
1067

From the 2021-09-07 survey

A targeted survey of nearshore and littoral fish species in Gervais Lake was conducted beginning on September 7th, 2021 by Index of Biological Integrity (IBI) Program Staff. Sampling sites were evenly spaced around the lake and each was sampled by backpack electrofishing and seining with a 50-foot or 15-foot seine,…

Source: MN DNR LakeFinder Fisheries Lake Survey

DNR Reports & Resources

Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Gervais Lake. 2 reports on file.

EPA Impairment Status

Gervais Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).

Causes of impairment

Impaired biota (cause unknown)MercuryPFASSalinity / chlorides

A Total Maximum Daily Load (TMDL) plan has been approved.

Source: EPA ATTAINS assessment unit MN62-0007-00 · Official waterbody report

Data Sources

Water quality data from the EPA Water Quality Portal

Impairment status from EPA ATTAINS 303(d) database

Grading methodology based on Metropolitan Council standards

Lake details from Minnesota DNR LakeFinder

Ice data from Minnesota DNR Climate

Most recent sample: 2024-09-17

Monitoring stations: 1